NORTH CASTLE - Anyone driving on Routes 22 or 120 in Armonk on Monday afternoon or evening may have wondered what all the police, fire and helicopter activity was about.

Those first responders teamed up to extinguish a brush fire that burned part of the Kensico Reservoir peninsula as temperatures hit 90 degrees.

The fire was reported at 3:42 p.m. in the peninsula off Route 120, Armonk Fire Chief Phil Goulet said. Armonk and Thornwood firefighters responded, and a Westchester County police helicopter crew helped find the fire, which spanned an area about 30 feet by 30 feet, he said.

The helicopter team dropped water about 15 times on the fire while firefighters used Department of Environmental Protection boats to get there, Goulet said. Firefighters cleared the scene around 8 p.m.

The DEP and Westchester County Cause and Origin Team are investigating the cause of the fire.